The surface profile of a material is a combination of roughness, waviness, and form. To produce bearing surfaces that meet performance requirements, conventional surface finishing reduces the roughness by polishing the ground bearing surfaces, such as pins and main bearing journals on an automotive crankshaft. An automotive crankshaft 10 is shown in FIG. 1. The automotive crankshaft 10 includes crankshaft bearings 12 and connecting rod bearings 14. Connecting rods 16 connect the crankshaft 10 to pistons 18. As the pistons 18 translate within the engine cylinders (not shown), the connecting rods 16 transfer rotational force to the crankshaft 10 via the connecting rod bearings 14. The crankshaft 10 rotates within the connecting rod bearings 14 and the crankshaft bearings 12. The crankshaft 10 rotates a flywheel 20 to transfer the rotational force to a vehicle transmission.
Connecting rods and main bearing shells of the crankshaft journal are subject to high tribological stress. Therefore, crankshafts, crankshaft bearings, and connecting rod bearings are highly susceptible to wear and deterioration due to heat, pressure, abrasion, and loss of lubrication. Conventionally, bearing surfaces on the crankshaft are polished using a combination of rotating and grinding to reduce the roughness of the crankshaft bearing surfaces. The crankshaft is polished using an abrasive material to remove inclusions, such as carbon nodules and dirt, that are embedded in the crankshaft surface during the manufacturing process. The abrasive material, such as abrasive tape or stone, removes the inclusions, but often leaves a relatively large open pore in the surface. The polishing process may then rub metal over these open pores, partially covering the pores with a projecting edge. These projecting edges are commonly called “ferrite caps” or “hooks.” After assembly in an engine, these ferrite caps may break off, forming small abrasive particles that lead to premature bearing failure. The process to eliminate ferrite caps includes reversing the rotation of the crankshaft during the polishing.